One of my fond memories from being an undergraduate in the early 1990s was the fervent conviction of the campus left that their opponents were not entitled to express their beliefs. Some of the more erudite among them, like Catherine MacKinnon, would formulate elaborate theories explaining why freedom of speech was a pernicious myth. But mostly the opinion took the form of slogans. Racism is not free speech. Sexism is not free speech. And since anybody to the right of, oh, Ralph Nader was a racist and a sexist, then that meant that nobody outside of the left-wing ought to be permitted to express themselves.
The principle, if you can call it that, was on display at Israeli Ambassador Michael Oren's speech at the University of California-Irvine. I'm not a big Michael Oren fan, but this display of protesters disrupting his remarks is rather telling:
The slogan of the protesters here was "Michael Oren! Propagating murder is not an expression of free speech!" Of course, you will note that at no point in Oren's speech does he murder anybody. So, we are back to the foundational belief that free speech ought not to apply to anybody who expresses views the campus left dislikes.